concatenate text w/ date

here's an example:

1.=CONCATENATE("Net Asset Value at"," ",TEXT(a3,"mmmm dd, yyyy"))

2.=CONCATENATE("Net Asset Value at"," ",TEXT(a3,"mmmm dd, yyyy"))

where 1. is the beginning date, 2. is the ending date and A3 is the link
to the ending date.

what string could i use for the beginning date? (right now i just use "minus 30" after A3 but
that only works with 30 days in the calendar month.